Indexed fields as spans

[gatesy]

This PR exposes an array field as a ReadOnlySpan.

This was motivated by the need to store a GUID in a field. The natural way to do this is using a field of 16 bytes, which means the way to extract and encode it requires copying to an intermediate array. The C# GUID struct provides a ReadOnlySpan constructor, allowing us to create a GUID without copying to an intermediate byte buffer, e.g.:

var guid = new Guid(message.Guid);

and for encoding store:

var guidBytes = Guid.NewGuid().ToByteArray();

then set it using:

message.Guid = new ReadOnlySpan<byte>(guidBytes);

I've also added an AsSpan() method, to support writing directly from a Guid object to the underlying array. This allows you to write a Guid like this:

guid.TryWriteBytes(message.GuidAsSpan());

[mjpt777]

@billsegall Do you have any views on this?

[billsegall]

I think it's a useful helper function. I see no compatibility issues.

[gatesy]

Could we get this change merged up and a new version of the sbe-tool NuGet package published? Is there anything I can help with to get this done?

[billsegall]

A new nuget release is probably due. I'll do that post merge. Bill.

…

On Sat, 16 May 2020 at 20:44, Dr. James Gate ***@***.***> wrote: Could we get this change merged up and a new version of the sbe-tool NuGet package published? Is there anything I can help with to get this done? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#780 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABJDLJACW5US2QMGFCN5UETRRZU65ANCNFSM4NAFIKEA> .

[billsegall]

I've done a nuget release as 1.17.1. Consistent versioning across all backend languages is a little tricky.